CN108647449A - A kind of Cohesive Sediment motion value analogy method based on flocculation kinetics - Google Patents
A kind of Cohesive Sediment motion value analogy method based on flocculation kinetics Download PDFInfo
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Abstract
The present invention provides a kind of Cohesive Sediment motion value analogy method based on flocculation kinetics, including (1) generates Un-structured triangle gridding, including main stem and seashore part according to bed configuration；(2) according to the hydraulic elements of each grid of flow cavitation result equation calculation, upstream and downstream boundary condition and channel roughness are provided in calculating process；(3) Cohesive Sediment particle diameter distribution and the situation of change of silt-settling velocity after flocculating are calculated；(4) sediment concentration and change in bed level situation of change of corresponding grid are obtained；(5) calculating of step (2)~(4) until completing the entire period is repeated, the entire motion process of Cohesive Sediment is simulated, provides channel deposits field distribution and change in bed level variation.The present invention simulates the silt distribution field calculated under the conditions of the variation of Cohesive Sediment particle diameter distribution and different hydrodynamic, it solves the problems, such as the quasi- middle ignorance of the defeated shifting formwork of Cohesive Sediment or simplifies to flocculate to influence, a kind of important technological means is provided for accurate simulate that Cohesive Sediment moves.
Description
Technical field
The Cohesive Sediment motion value analogy method based on flocculation kinetics that the present invention relates to a kind of, belongs to sediment movement
Numerical simulation technology field.
Background technology
The Cohesive Sediment being widely present with suspended state in natural water body is metal cation, flow, the organic matter the effects that
Under flocculation can occur form silt floc sedimentation, Cohesive Sediment flocculation changes Cohesive Sediment existence form, particle diameter distribution, sinking speed,
It affects Cohesive Sediment and moves defeated shifting characteristic, therefore, Cohesive Sediment moves the defeated research for moving characteristic and is concerned in recent years.
However, since Cohesive Sediment flocculation process is complicated and impact factor is numerous, often adopted in existing sediment movement model
With ignoring or embodying flocculated influence only by the mode for changing settling velocity simplification processing, this processing method is to a certain extent
The computational accuracy for affecting model limits the application of model.
Therefore, in order to which more accurate comprehensive description Cohesive Sediment moves defeated shifting situation, there is an urgent need for establish a kind of coupling flocculation
The model system of dynamics and traditional sediment dynamics.
Invention content
The present invention is to build Cohesive Sediment motion mathematical model, simulation on the basis of considering Cohesive Sediment flocculating properties
The silt distribution field under the conditions of the variation of Cohesive Sediment particle diameter distribution and different hydrodynamic is calculated, solves the defeated shifting formwork of Cohesive Sediment
Ignore or simplify the problem of flocculation influences in quasi-, a kind of important technological means is provided for the accurate simulation of Cohesive Sediment movement.
In order to solve the above technical problems, the technical solution adopted by the present invention is as follows：
Technical scheme of the present invention：A kind of Cohesive Sediment motion value analogy method based on flocculation kinetics, it is described
Method for numerical simulation includes the following steps：
(1) according to bed configuration, Un-structured triangle gridding, including main stem and seashore part are generated；
(2) according to the hydraulic elements of each grid of flow cavitation result equation calculation, including flow, flow velocity, water level and the depth of water, meter
Upstream and downstream boundary condition and channel roughness are provided during calculating；
(3) flow shear strength is calculated using hydraulic elements, then according to flocculation kinetics equation, in conjunction with the flow
Shear strength and given incipient sediment particle diameter distribution and physico-chemical property parameter, calculate flocculation after Cohesive Sediment particle diameter distribution and
The situation of change of silt-settling velocity；
(4) according to viscosity after the given sediment concentration of upstream boundary, the hydraulic elements of each grid, the flocculation
Distribution of sediment and silt-settling velocity calculate sediment clouds and river-bed deformation equation, obtain corresponding grid sediment concentration and
Change in bed level situation of change；
(5) calculating of step (2)~(4) until completing the entire period is repeated, the entire motion process of Cohesive Sediment is simulated, gives
Go out channel deposits field distribution and change in bed level variation.
The flow cavitation result equation of the step (2) is planar Shallow-water Flow governing equation group, the upstream and downstream perimeter strip
Part includes flow and water level process；Planar Shallow-water Flow governing equation group is expressed as：
In formula：X, y are coordinate system coordinate；T is the time；Ux、UyThe average speed of respectively x and y-axis to flow；H is total water
It is deep, h=d+z, wherein d is the static depth of water, and z is water level, and g is acceleration of gravity；υtFor turbulent viscosity；C is to thank to be
Number, C=1/nh(1/6), n is Manning roughness coefficient.
The flocculation kinetics equation of the step (3) is PBM equations, and PBM equations are：
In formula：V and u is floc sedimentation volume；N (v) indicates that volume is the silt floc sedimentation number of v；α (v, u) and β (v, u) is respectively
Indicate that volume is respectively the collision efficiency and collision frequency of two floc sedimentations of v and u；δ (v) indicates that volume is the break-up frequency of v floc sedimentations；
γ2(v, u) indicates the broken probability function for generating the floc sedimentation that volume is v of floc sedimentation that volume is u；First item indicates body on the right of equation
The particle that product is v-u and u/floc sedimentation generates the rate that volume is v floc sedimentations；Section 2 indicates the floc sedimentation and other floc sedimentations that volume is v
Collision bonds the minimizing speed for leading to v floc sedimentation numbers；Section 3 indicates the broken rate for generating v floc sedimentations of floc sedimentation of the volume more than v；
Section 4 indicates the broken caused v floc sedimentation number minimizing speeds of v floc sedimentations.
The Cohesive Sediment physico-chemical property parameter of the step (3) includes between silt floc sedimentation fractal dimension, sand grain
Cohesive force.
The silt-settling velocity of the step (3) is according to the equation for considering silt floc sedimentation fractal propertyIt calculates, wherein：ωkFor the silt-settling velocity of kth grain size group silt floc sedimentation, μ is
Water body dynamic viscosity；d0For incipient sediment grain diameter；G is acceleration of gravity；dkFor silt floc sedimentation grain size；ρsAnd ρwRespectively
Sand grain and water body density；nkInclude primary particles number for kth grain size group silt floc sedimentation；DFFor silt floc sedimentation fractal dimension.
The sediment clouds of the step (4) are using grouping suspended load unbalanced sediment transport equation, i.e.,
In formula：SkFor the silt content of kth grain size group silt；ωkFor the settling velocity of kth grain size group silt；S*kFor k grain size group mud
Husky sand holding ability, εsFor sediment diffusion equation；FKFor kth grain size group Sedimentation item, mainly with bottom shear power and sediment Characteristics
Correlation can be calculated with following formula
In formula：αsiFor kth grain size group silt restoration ＆ saturation coefficient；τ is flow bottom shear power；τdkFor kth grain size group mud
Husky non silting velocity circle shear stress；M is suspension coefficient of discharge；τekFor kth grain size group sediment incipient motion critical shearing stress.
The river-bed deformation equation of the step (4) is as follows：
In formula, Δ zbFor bed material erosion and deposition thickness；ρdFor silt dry density；Δ t is time step；FKFor kth grain size group mud
Husky erosion and deposition item.
The beneficial effects of the invention are as follows：The basic thought of the present invention is, based on Cohesive Sediment particle characteristics, traditional
On the basis of sediment bypassing model, silt flocculating modules are added, it is accurate to simulate distribution of sediment etc. in Cohesive Sediment flocculation process
Variation, and by silt floc sedimentation fractal structure characteristic be introduced into settling velocity calculate in, can accurately more simulate the movement of Cohesive Sediment,
It makes up previous research and is ignoring or simplifying some shortcomings present on silt flocculation influence.
Description of the drawings
Fig. 1 method for numerical simulation flow charts of the present invention；
Fig. 2 Cohesive Sediments flocculation equation principle schematic；
Fig. 3 Cohesive Sediment flocculating modules verification results；
The Cohesive Sediment initial particle grading that Cohesive Sediment motion model verifications of the Fig. 4 based on flocculation kinetics uses；
Cohesive Sediment motion model verification results of the Fig. 5 based on flocculation kinetics.
Specific implementation mode
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation describes, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
Referring to Fig. 1, technical scheme of the present invention：
A kind of Cohesive Sediment motion value analogy method based on flocculation kinetics, the method for numerical simulation include such as
Lower step：
(1) according to bed configuration, Un-structured triangle gridding, including main stem and seashore part are generated；
(2) according to the hydraulic elements of each grid of flow cavitation result equation calculation, including flow, flow velocity, water level and the depth of water, meter
Upstream and downstream boundary condition and channel roughness are provided during calculating；
(3) flow shear strength is calculated using hydraulic elements, then according to flocculation kinetics equation, in conjunction with the flow
Shear strength and given incipient sediment particle diameter distribution and physico-chemical property parameter, calculate flocculation after Cohesive Sediment particle diameter distribution and
The situation of change of silt-settling velocity；
(4) according to viscosity after the given sediment concentration of upstream boundary, the hydraulic elements of each grid, the flocculation
Distribution of sediment and silt-settling velocity calculate sediment clouds and river-bed deformation equation, obtain corresponding grid sediment concentration and
Change in bed level situation of change；
(5) calculating of step (2)~(4) until completing the entire period is repeated, the entire motion process of Cohesive Sediment is simulated, gives
Go out channel deposits field distribution and change in bed level variation.
Model cootrol equation
(1) flow cavitation result equation
Natural water area meet such as hydrostatic pressure distribution, table, vertical acceleration is smaller and bed surface gradient is smaller
Assuming that with condition in the case of, its Hydrodynamic Process can be described using two-dimensional shallow water equation with plane.
Planar Shallow-water Flow governing equation group is represented by
In formula：X, y are coordinate system coordinate；T is the time；Ux、UyThe average speed of respectively x and y-axis to flow；H is total water
It is deep, h=d+z, wherein d is the static depth of water, and z is water level, and g is acceleration of gravity；υtFor turbulent viscosity；C is to thank to be
Number, C=1/nh(1/6), n is Manning roughness coefficient.
(2) sediment clouds
For particle size, Cohesive Sediment belongs to suspended load, and natural sand is nonuniform sediment, therefore silt in the present embodiment
The equation of motion is using grouping suspended load unbalanced sediment transport equation, i.e.,
In formula：SkFor the silt content of kth grain size group silt；ωkFor the settling velocity of kth grain size group silt；S*kFor k grain size group mud
Husky sand holding ability, εsFor sediment diffusion equation；FKRespectively kth grain size group Sedimentation item, mainly with bottom shear power and silt
Characteristic is related, can be calculated with following formula
In formula：αsiFor kth grain size group silt restoration ＆ saturation coefficient；τ is flow bottom shear power；τdkFor kth grain size group mud
Husky non silting velocity circle shear stress；M is suspension coefficient of discharge；τekFor kth grain size group sediment incipient motion critical shearing stress.
(3) river-bed deformation equation
The bed deformation amount caused by Cohesive Sediment unbalanced sediment transport can be calculated by following formula：
In formula, Δ zbFor bed material erosion and deposition thickness；ρdFor silt dry density.
(4) flocculation kinetics equation
The flocculation kinetics equation that Smoluchowski in 1971 is proposed is the basis for establishing flocculation kinetics model at present,
But the factors such as floc sedimentation is broken are not considered in this equation, therefore use improved PBM (Population in the present embodiment
Balance Model) equation, i.e.,
In formula：V and u is floc sedimentation volume；N (v) indicates that volume is the silt floc sedimentation number of v；α (v, u) and β (v, u) is respectively
Indicate that volume is respectively the collision efficiency and collision frequency of two floc sedimentations of v and u；δ (v) indicates that volume is the break-up frequency of v floc sedimentations；
γ2(v, u) indicates the broken probability function for generating the floc sedimentation that volume is v of floc sedimentation that volume is u.First item indicates body on the right of equation
The particle (floc sedimentation) that product is v-u and u generates the rate that volume is v floc sedimentations；Section 2 indicates the floc sedimentation and other floc sedimentations that volume is v
Collision bonds the minimizing speed for leading to v floc sedimentation numbers；Section 3 indicates the broken rate for generating v floc sedimentations of floc sedimentation of the volume more than v；
Section 4 indicates the broken caused v floc sedimentation number minimizing speeds of v floc sedimentations.
(5) subsidiary equation
1) settling velocity calculation formula
For thicker silt individual particle, calculated using traditional Stokes settling velocity formula.Silt floc sedimentation generally has
Higher porosity and complicated fractal structure, settling velocity cannot use traditional sediment settlement formula directly to calculate, this implementation
Using the settling velocity calculation formula for considering Floe structure form in example, i.e.,
In formula：μ is water body dynamic viscosity；d0For incipient sediment grain diameter；dkFor silt floc sedimentation grain size；ρsAnd ρwRespectively
For sand grain and water body density；nkInclude primary particles number for kth grain size group silt floc sedimentation；DFFor silt floc sedimentation FRACTAL DIMENSION
Number.
2) turbulent viscosity
For water front compares the section of smooth-going, turbulent viscosity, which can omit, to be disregarded, but drastically to Shoreline changes, is had back
The raw section of miscarriage, the selection of turbulent viscosity seem very crucial, this is because the generation of reflux is existed with vertical face
Premised on frictional resistance, therefore turbulent viscosity is to determine the key parameter to flow back whether occur in practical fluidised form, they
Value and flow condition, sizing grid etc. are related.According to Sgorinsky formula, turbulent viscosity
Wherein：Δ-sizing grid；
Cs- Smagorinsky coefficients, it is proposed that value 0.25~1.0；
Since Cohesive Sediment diffusion coefficient and flow turbulence viscosity have identical physical substance, glued in the present embodiment
Property sediment diffusion equation be equal to flow turbulence viscosity.
2) collision frequency calculation formula
Collision frequency reflects the parameter of collision rate between silt individual particle (floc sedimentation).Equally using consideration in the present embodiment
The formula that floc sedimentation fractal structure influences calculates collision frequency (Du G L, Bonner J S, Garton L S, et
al.Modeling coagulation kinetics incorporating fractal theories:a fractal
rectilinear approach[J].Water Research,2000,34(7):1987-2000), calculation formula is as follows
βij=βDS(ij)+βFS(ij) (8)
In formula：βDSAnd βFSCollision frequency respectively under differential sedimentation and flow action；v0For the volume of silt individual particle；
G is flow shear strength, with turbulent energy dissipation factor ε and liquid motion viscosity (μ/ρw) in relation to (G=(ρwε/μ)1/2), according to
U=(μ/ρwε)1/4The relationship of G and flow rate of water flow can be established.
3) collision efficiency calculation formula
For the Cohesive Sediment of micron level, when two particles close to when, with grain spacing from the hydrodynamic(al) being inversely proportional
Kinetic forces will prevent its close, and when the distance between two particles are close, London forces occupy leading position, therefore, water
Power, which acts on, and London forces are influences the principal element of sand grain collision efficiency.According to particles collision curvilinear path correlative study
Achievement (Han M, Lawler D F.The (Relative) Insignificance of G in Flocculation [J]
.Journal American Water Works Association,1992,84(10):79-91.), under collision efficiency is available
Formula calculates
In formula：αDSAnd αFSCollision efficiency respectively under differential sedimentation and flow shear action；λ is two close particles
Grain size ratio, 0<λ≤1；b1,c1,d1,e1,b2,c2,d2And e2For correlation computations coefficient, concrete form can refer to following documents (Li
X Y,Zhang J.J.Numerical simulation and experimental verification of particle
coagulation dynamics for a pulsed input[J].Journal of Colloid and interface
Science,2003,262(1):149-161)。
4) break-up frequency and mode calculation formula
Its bigger intensity of silt size of flocculate is smaller, can be crushed under the action of flow shear.In the present embodiment
Floc sedimentation break-up frequency (Peng S J, Willoams R A.Direct are calculated using widely applied semiempirical formula
measurement of floc breakage in flowing suspensions[J].Journal of Colloid and
Interface Science,1994,166(2):321-332), i.e.,
In formula：A ' is correction coefficient；y1It is generally to take 1.6 with the relevant parameter of Floc strength.
Floc sedimentation occurs after being crushed, and crumbling method has binary to be crushed, ternary is broken and normal state is three kinds broken, in the present embodiment
Using with normal state crumbling method similar in reality, be expressed as with formula
In formula：vaFor the average external volume of sub- floc sedimentation；σfFor the standard deviation of sub- floc sedimentation particle diameter distribution, wherein va=vj/2、σf=
vj/10(Zhang,J J,Li X Y.Modeling particle-size distribution dynamics in a
flocculation system[J].AIChE J,2003,49:1870-1882)。
Embodiment 3
Equation is discrete and computational methods
(1) equation is discrete
1) water sand control equation
Using the discrete Water-sand model governing equation of finite volume method under unstructured P2P network.
2) flocculation kinetics equation
The accuracy of flocculation kinetics equation calculation directly affects the precision of entire analogy method, selects suitable discrete side
Method is highly important.V is used in the present embodimentk+1=21/qvk(q is parameter) is discrete to the progress of flocculation kinetics equation, in turn
The type of k grain size group silt floc sedimentation number of variations can will be caused to be divided into 7 kinds, respectively：Wadding between Class1 particles (floc sedimentation)
It is solidifying to generate the floc sedimentation of the sections k and rank less than the sections k；Flocculation between 2. particle of type (floc sedimentation) only generates the floc sedimentation in the sections k；
Type 3：Flocculation between particle (floc sedimentation) generates the sections k and rank is more than the floc sedimentation in the sections k；Type 4：Between particle (floc sedimentation)
Flocculation make the floc sedimentation partial disappearance in the sections k；Type 5：Flocculation between particle (floc sedimentation) makes the floc sedimentation in the sections k all disappear；
Type 6：Grain size rank is more than the broken floc sedimentation for generating the sections k of floc sedimentation in the sections k；Type 7：Caused by the floc sedimentation in the sections k is broken
Loss, is expressed as with mathematical formulae
In formula：S (i) be and the relevant coefficients of q, S (i)=[1-qln (1-2-i/q)/ln2]。
(2) computational methods
Water flow sediment movement equation is calculated using SIMPLE methods, and flocculation equation uses the Runge-Kutta of adaptive step
Method calculates.
Model is verified
(1) flocculating modules are verified
For Cohesive Sediment flocculating modules, verified using the data in document.
Incipient sediment size grading is in 5~20 μm, initial concentration 0.5kg/m in experiment3, flow shear strength G=5,
10、20、40s-1。
When calculating, using identical incipient sediment particle diameter distribution, initial concentration and flow shear strength with experiment, mud is selected
For husky floc sedimentation particle diameter distribution for verifying, the related parameter values that when calculating uses are as shown in table 1.
The verification of 1 flocculating modules of table calculates relevant parameter
| Parameter | Unit | Numerical value |
| μ | Pa·s | 1.005×10-3 |
| ρs | kg/m3 | 2.65×103 |
| ρw | kg/m3 | 1.0×103 |
| g | m/s2 | 9.81 |
| G | s-1 | 5、10、20、40 |
| DF | 2.1 | |
| A’ | 0.15~0.23 | |
| y1 | 1.6 | |
| q | 1 |
Verification result is as shown in Figure 3, it is known that flocculating modules can preferably simulate floc sedimentation grain size in Cohesive Sediment flocculation process
The situation of change of distribution.
(2) the Cohesive Sediment motion model verification based on flocculation kinetics
It is husky using selection entrance of Changjiang River Xuliujing Reach section and white cogongrass for the Cohesive Sediment motion model based on flocculation kinetics
Branch of a river road section field data is verified.
In calculating, landform is originated using in November, 2011, is calculated in September, 2014.It is real using big logical station to calculate coboundary
Measurement of discharge and silt discharge data, as shown in table 1, lower boundary use the actual measurement tide gauge of corresponding control station, Cohesive Sediment initial
Particle diameter distribution is as shown in Figure 4.
2 coboundary water sand process of table is generally changed
| Number | Beginning and ending time (date) | Flow (m3/s) | Number of days (day) | Silt discharge (t/s) |
| 1 | 2011/11/26~2011/12/31 | 16536 | 37 | 1.182 |
| 2 | 2012/01/01~2012/02/22 | 14430 | 53 | 1.009 |
| 3 | 2012/02/23~2012/04/14 | 22754 | 52 | 3.241 |
| 4 | 2012/04/15~2012/05/23 | 37756 | 39 | 5.712 |
| 5 | 2012/05/24~2012/07/12 | 47942 | 50 | 7.479 |
| 6 | 2012/07/13~2012/09/16 | 49688 | 66 | 11.468 |
| 7 | 2012/09/17~2012/11/12 | 28330 | 57 | 3.409 |
| 8 | 2012/11/13~2012/12/31 | 20673 | 49 | 2.258 |
| 9 | 2013/01/01~2013/03/20 | 16666 | 79 | 1.394 |
| 10 | 2013/03/20~2013/04/23 | 24159 | 34 | 3.964 |
| 11 | 2013/04/24~2013/05/25 | 30197 | 32 | 5.521 |
| 12 | 2013/05/26~2013/07/03 | 41361 | 39 | 6.127 |
| 13 | 2013/07/04~2013/07/18 | 42400 | 15 | 6.324 |
| 14 | 2013/07/19~2013/08/23 | 36819 | 36 | 9.909 |
| 15 | 2013/08/24~2013/09/16 | 27683 | 24 | 3.430 |
| 16 | 2013/09/17~2013/10/31 | 22358 | 45 | 2.295 |
| 17 | 2013/10/31~2013/12/31 | 12600 | 61 | 0.942 |
| 18 | 2014/01/01~2014/02/28 | 11614 | 59 | 0.554 |
| 19 | 2014/03/01~2014/04/14 | 16514 | 45 | 1.463 |
| 20 | 2014/04/15~2014/05/12 | 25946 | 28 | 3.239 |
| 21 | 2014/05/13~2014/05/30 | 36911 | 18 | 6.268 |
| 22 | 2014/05/31~2014/06/07 | 41288 | 8 | 9.135 |
| 23 | 2014/06/08~2014/08/31 | 38752 | 85 | 4.990 |
The silt content for extracting different location carries out calculated value and measured value comparison, and verification result by verification as shown in figure 5, tied
Fruit considers that the silt content calculated value with measured value of check post after flocculating coincide more as it can be seen that compared with not considering flocculated calculated value
Good, the erosion and deposition regularity of distribution is similar with recent actual measurement landform scour-silting rule.
It although an embodiment of the present invention has been shown and described, for the ordinary skill in the art, can be with
Understanding without departing from the principles and spirit of the present invention can carry out these embodiments a variety of variations, modification, replace
And modification, the scope of the present invention is defined by the appended.
Claims (7)
1. a kind of Cohesive Sediment motion value analogy method based on flocculation kinetics, which is characterized in that the numerical simulation
Method includes the following steps：
(1) according to bed configuration, Un-structured triangle gridding, including main stem and seashore part are generated；
(2) it according to the hydraulic elements of each grid of flow cavitation result equation calculation, including flow, flow velocity, water level and the depth of water, calculated
Upstream and downstream boundary condition and channel roughness are provided in journey；
(3) flow shear strength is calculated using hydraulic elements, then according to flocculation kinetics equation, is sheared in conjunction with the flow
Intensity and given incipient sediment particle diameter distribution and physico-chemical property parameter calculate Cohesive Sediment particle diameter distribution and silt after flocculation
The situation of change of settling velocity；
(4) according to Cohesive Sediment after the given sediment concentration of upstream boundary, the hydraulic elements of each grid, the flocculation
Particle diameter distribution and silt-settling velocity calculate sediment clouds and river-bed deformation equation, obtain the sediment concentration and riverbed of corresponding grid
Scour and Accretion situation；
(5) calculating of step (2)~(4) until completing the entire period is repeated, the entire motion process of Cohesive Sediment is simulated, provides river
Road silt field distribution and change in bed level variation.
2. according to the method described in claim 1, it is characterized in that, the flow cavitation result equation of the step (2) is planar
Shallow-water Flow governing equation group, the upstream and downstream boundary condition includes flow and water level process；Planar Shallow-water Flow governing equation
Group is expressed as：
In formula：X, y are coordinate system coordinate；T is the time；Ux、UyThe average speed of respectively x and y-axis to flow；H is total depth of water, h
=d+z, wherein d is the static depth of water, and z is water level, and g is acceleration of gravity；υtFor turbulent viscosity；C is to thank ability coefficient, C=
1/n·h(1/6), n is Manning roughness coefficient.
3. according to the method described in claim 1, it is characterized in that, the flocculation kinetics equation of the step (3) is the side PBM
Journey, PBM equations are：
In formula：V and u is floc sedimentation volume；N (v) indicates that volume is the silt floc sedimentation number of v；α (v, u) and β (v, u) are indicated respectively
Volume is respectively the collision efficiency and collision frequency of two floc sedimentations of v and u；δ (v) indicates that volume is the break-up frequency of v floc sedimentations；γ2
(v, u) indicates the broken probability function for generating the floc sedimentation that volume is v of floc sedimentation that volume is u；First item indicates volume on the right of equation
The rate that volume is v floc sedimentations is generated for particle/floc sedimentation of v-u and u；Section 2 indicates that volume is that the floc sedimentation of v is touched with other floc sedimentations
Hit the minimizing speed for bonding and leading to v floc sedimentation numbers；Section 3 indicates the broken rate for generating v floc sedimentations of floc sedimentation of the volume more than v；The
Four indicate the broken caused v floc sedimentation number minimizing speeds of v floc sedimentations.
4. according to the method described in claim 1, it is characterized in that, the Cohesive Sediment physico-chemical property parameter packet of the step (3)
Include the cohesive force between silt floc sedimentation fractal dimension, sand grain.
5. according to the method described in claim 1, it is characterized in that, the silt-settling velocity of the step (3) is wadded a quilt with cotton according to consideration silt
The equation of group's fractal propertyIt calculates, wherein：ωkIt wads a quilt with cotton for kth grain size group silt
The silt-settling velocity of group, μ are water body dynamic viscosity；d0For incipient sediment grain diameter；G is acceleration of gravity；dkFor silt floc sedimentation grain
Diameter；ρsAnd ρwRespectively sand grain and water body density；nkInclude primary particles number for kth grain size group silt floc sedimentation；DFFor mud
Husky floc sedimentation fractal dimension.
6. according to the method described in claim 1, it is characterized in that, the sediment clouds of the step (4) are outstanding using grouping
Matter unbalanced sediment transport equation is moved, i.e.,
In formula：SkFor the silt content of kth grain size group silt；ωkFor the settling velocity of kth grain size group silt；S*kIt is held under the arm for k grain size group silts
Sha Li, εsFor sediment diffusion equation；FKFor kth grain size group Sedimentation item, mainly with bottom shear power and sediment Characteristics phase
It closes, can be calculated with following formula
In formula：αsiFor kth grain size group silt restoration ＆ saturation coefficient；τ is flow bottom shear power；τdkNot for kth grain size group silt
Silt critical shearing stress；M is suspension coefficient of discharge；τekFor kth grain size group sediment incipient motion critical shearing stress.
7. according to the method described in claim 6, it is characterized in that, the river-bed deformation equation of the step (4) is as follows：
In formula, Δ zbFor bed material erosion and deposition thickness；ρdFor silt dry density；Δ t is time step；FKFor kth grain size group Sedimentation
.
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